Gastroenteritis is an inflammation of your stomach and intestines. Common causes are:

Viruses.

Food or water contaminated by bacteria or parasites.

Reaction to a new food. Young children may develop signs and symptoms for this reason. Infants who are breast-fed may even react to a change in their mothers' diets.

Side effect from medications.

Characteristic signs and symptoms include:

Nausea or vomiting

Diarrhea

Abdominal cramps

Low-grade fever (sometimes)

Depending on the cause of the inflammation, symptoms may last from one day to more than a week.

If you suspect gastroenteritis in yourself:

Stop eating for a few hours to let your stomach settle.

Drink plenty of liquids, such as a sports drink or water, to prevent dehydration. If you have trouble tolerating liquids, take them in frequent sips. Make sure that you're urinating normally and that your urine is light and clear — not dark. Infrequent passage of dark urine is a sign of dehydration. Dizziness and lightheadedness also are signs of dehydration. If any of these signs and symptoms occur and you can't drink enough fluids, seek medical attention.

Consider acetaminophen (Tylenol, others) for relief of discomfort, unless you have liver disease.

Get plenty of rest. The illness and dehydration can make you weak and tired.

Get medical help if:

Vomiting persists more than two days

Diarrhea persists more than several days

Diarrhea turns bloody

Fever is 101 F (38.3 C) or higher

Lightheadedness or fainting occurs with standing

Confusion develops

Worrisome abdominal pain develops

If you suspect gastroenteritis in your child:

Allow your child to rest.

When your child's vomiting stops, begin to offer small amounts of an oral rehydration solution (CeraLyte, Enfalyte, Pedialyte). Don't use only water or only apple juice.

Gradually introduce bland, easy-to-digest foods, such as toast, rice, bananas and potatoes. Avoid giving your child full-fat dairy products, such as whole milk and ice cream, and sugary foods, such as sodas and candy. These can make diarrhea worse.

If you're breast-feeding, let your baby nurse. If your baby is bottle-fed, offer a small amount of an oral rehydration solution or regular formula.

Get medical help if your child:

Becomes unusually drowsy.

Vomits blood.

Has bloody diarrhea.

Shows signs of dehydration, such as dry mouth and skin, marked thirst, sunken eyes, or crying without tears. In an infant, be alert to the soft spot on the top of the head becoming sunken and to diapers that remain dry for more than three hours.

Is younger than age 2 and has a fever that lasts more than one day or is age 2 or older and has a fever that lasts more than three days.

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